Shock absorber with stanchion mounted bypass damping

ABSTRACT

A dampener (628) for a shock absorber of a vehicle, such as a bicycle, is mounted within a telescoping front fork including a stanchion tube (116) and a coaxial slide tube (618). The dampener includes an internally received hydraulic fluid sleeve (640) that defines a hydraulic chamber (648) in which a piston assembly (732) is disposed. Movement of the piston assembly through hydraulic fluid within the hydraulic chamber is selectively adjusted by metering the flow of bypass hydraulic fluid to the back side of the piston assembly by adjusting a responsive valve assembly (670) disposed longitudinally within the stanchion tube. The responsive valve assembly includes a piezoelectric bender (702) that is controlled by circuitry (712) to change its biasing relative to a valve member (694) in response to sensed velocity and/or displacement of the piston assembly.

RELATED APPLICATIONS

This is a continuation-in-part of U.S. patent application Ser. No.08/891,528 filed Jul. 11, 1997, which is a continuation-in-part of U.S.patent application Ser. No. 08/857,125 filed May 15, 1997.

FIELD OF THE INVENTION

The present invention relates to shock absorbers for vehicles, such asbicycles and motorcycles, and more particularly, to a dampener valve fora shock absorber to regulate the flow of damping fluid based on feedbackregarding velocity and displacement of the shock absorber shaft relativeto the shock absorber body.

BACKGROUND OF THE INVENTION

Front and rear suspensions have improved the performance and comfort ofmountain bicycles. Over rough terrain the suspension system can improvetraction and handling by keeping the wheels on the ground. A rider canmore easily maintain control at higher speeds and with less effort whenthe suspension absorbs some of the shock encountered when riding.Ideally the suspension should react well to both (1) low amplitude, highfrequency bumps and (2) high amplitude, low frequency bumps. However,these can be competing requirements for the damping systems inconventional shock absorbers.

Higher rebound damping is desirable for high amplitude, low frequencybumps than for low amplitude, high frequency bumps. With high frequency,low amplitude bumps, such as may be encountered on a washboard gravelfireroad, minimal damping may be preferable so the spring can quicklyrecover from a minor impact before the next is encountered. However,with a large bump (such as the size of a curb) increased rebound dampingaids the rider by keeping the bike from forcefully springing back tooquickly, causing loss of traction and control on the rebound.Compression damping will also stop the bike from bottoming out withlarge bumps and make for a smoother absorption of the bumps.

Some current shock absorbers that include springs and dampeners allowthe rider to adjust rebound and/or compression damping before a ride.Other air shock absorbers include an on/off switch to disable the shockabsorber all together. However, such preadjustment is at best acompromise; the rider must select better damping in one scenario at theexpense of the other. A typical off-road mountain bike ride will includesmall bumps, medium, and large bumps, as well as possibly jumps,drop-offs, and tight descending to ascending transitions. If the ridersignificantly reduces the damping to ride smoothly over high frequency,low amplitude bumps then the bike may lose traction and control when alarge bump is encountered or may "bottom out" the shock absorber. If therider increases the damping force of the shock absorber, then the systemwill not recover fast enough to quickly absorb high frequency bumps, therider will be rattled, and the bike will lose traction.

Another limitation of current shock absorbers is evidenced byrider-induced bobbing: suspension movement caused by rider movementduring pedaling. Related to this is pedal-induced suspension action: thecyclic forces on the chain pulling the rear swingarm up or down relativeto the frame. If the damping in the shock absorber is greater, theseinfluences will not be felt as much by the rider. However, a stiffsuspension, especially at the beginning of the stroke of the shockabsorber, can decrease the ability of the suspension to absorb smallbumps well.

Attempts to overcome the current limitations in suspension systems havefocused on swingarm linkages and pivot arrangements. At a significantcost, some amelioration of rider- or pedal-induced suspension action hasresulted, but much less progress has been made on the dilemma of largeand small bump absorption.

SUMMARY OF THE INVENTION

The present invention addresses the suspension challenges of both highfrequency/low amplitude and low frequency/high amplitude shockabsorption while also reducing rider- and pedal-induced suspensionaction. The present invention can be applied to most suspensionconfigurations as it addresses these challenges with a unique, activedamping shock absorber. The shock absorber is soft over small bumps andstiffens when encountering large shocks after the shock travels to acertain extent. The shock absorber stiffens further under extreme shockto avoid harsh bottoming out. Rebound damping may also be tunedindependent of compression damping. The shock absorber changes dampingduring compression and rebound according to the speed and displacementof the shaft assembly relative to the housing during the suspensionaction.

The present invention includes a dampener for a shock absorber. Thedampener preferably includes a fluid reservoir, a piston, a channel, anda valve. The fluid reservoir contains fluid for damping action of theshock absorber. The piston is disposed at least partially within thereservoir. The piston is forced at least partially through the reservoirunder the force of a shock acting on the shock absorber. The channel isin fluid communication with the reservoir. Fluid flows through thechannel during at least a portion of the stroke of the piston throughthe reservoir. The valve at least partially obstructs the channel. Thevalve includes a mechanism and control for changing the flow through thechannel based on at least one of the velocity and position of the pistonrelative to the reservoir.

In the preferred embodiment, the valve includes a bender. The bendermoves to affect the flow of fluid through the channel. The benderpreferably includes a response material embedded within at least aportion thereof.

In one preferred aspect of the invention, the valve includes a flowrestriction member and a diaphragm attached thereto. The bender ismoveable to direct a secondary flow of fluid to a side of the diaphragmto move the diaphragm. The diaphragm moves the restriction member. Aprimary flow of fluid passes through the channel as controlled by theflow restriction member.

In the preferred embodiment of the invention, the response materialincludes a piezoelectric material. The valve further includes a powersupply connected to the piezoelectric material for biasing the bender toaffect the flow through the channel. In one aspect of this embodiment, asensor is provided to detect shock compression conditions. The sensorchanges the biasing force of the bender for flow change when the sensorsignals predetermined conditions.

In one aspect of the invention, the flow restriction member is moveablegenerally transverse to the direction of fluid flow through a portion ofthe channel adjacent the restriction member. Preferably, the flowrestriction member is connected to the bender with movement of thebender controlling the flow restriction member.

In one aspect of the invention, the reservoir is contained by a housing.The channel extends through inflow and outflow openings or channelswithin the housing. Preferably, the inflow opening is located within thehousing in a location to be at least partially blocked by the pistonupon extensive movement or stroke of the piston within the reservoir orhousing. Preferably, the outflow opening is located within the housingin a location to be at least partially blocked by the piston during theinitial portion of the stroke of the piston. Thus, during extensivestroke of the piston within the reservoir the inflow opening or channelis at least partially blocked to increase the damping force. During theinitial portion of the stroke of the piston, the outflow opening orchannel is either at least partially blocked or opens to the first endof the piston whereas with further stroke of the piston within thereservoir, the outflow opening or channel transmits fluid to the secondend of the piston during compression of the piston within the reservoir.

In a further aspect of the present invention, a dampener is provided fora shock absorber including a stanchion tube. The dampener includes afluid chamber defined at least partially within the stanchion tube andwhich contains a fluid. A piston is disposed within the fluid chamberfor longitudinal movement within the fluid chamber under the force of ashock acting on the shock absorber, the piston having a first side and asecond side. A bypass channel is provided in fluid communication withthe fluid chamber on the first side of the piston and with the fluidchamber on the second side of the piston. The bypass channel permitsfluid to bypass the piston while flowing from the first side of thepiston to the second side of the piston. A valve is disposed within thestanchion tube and is operable to control the flow of fluid through thebypass channel.

In a still further aspect of the present invention, a dampener isprovided for a telescoping suspension strut of a vehicle having a groundengaging member, such as a wheel, and a frame. The dampener includes astanchion tube having an end securable to the ground engaging member orthe frame, and defining an internal fluid chamber. A piston assemblyincludes a piston disposed within the fluid chamber and a shaftextending therefrom that is securable to the other of the groundengaging member or frame. The piston has a first side and a second side,and moves within the fluid chamber under a force acting on thesuspension strut. A bypass channel is provided in fluid communicationwith the fluid chamber on the first side of the piston and with thefluid chamber on the second side of the piston, bypassing the pistontherebetween. A valve is disposed in fluid communication with the bypasschannel to automatically control the flow of fluid through the bypasschannel during movement of the piston assembly relative to the stanchiontube. The phrase "bypassing the piston" is used in this sense to mean afluid path which flows from one side of the piston to the other side ofthe piston without the necessity of flowing through compressiondampening passages and/or rebound dampening passages that are preferablyprovided within the piston.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many attendant advantages of this inventionwill become more readily appreciated as the same becomes betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevational view of the shock absorber of the presentinvention secured in the rear suspension of a bicycle;

FIG. 2A is a cross-sectional view of the shock absorber illustrated inFIG. 1;

FIG. 2B is a partial cross-sectional view of the shock absorberillustrated in FIG. 2A during a compression stroke;

FIG. 2C is a partial cross-sectional view of the shock absorber during arebound stroke;

FIG. 3A is an exploded view of the dampener valve assembly;

FIG. 3B is an isometric view of the piston body;

FIGS. 4A and 4B are a plan view and partial cross-sectional view,respectively, of the piezoelectric disk that is seated against the valvebody;

FIG. 5 is a plan view of an alternative embodiment of the valve discillustrated in FIGS. 4A and 4B;

FIG. 6 is a schematic diagram of the logic circuit used to control thepiezoelectric disk illustrated in FIGS. 4A and 4B;

FIG. 7A graphically illustrates damping force versus shaft velocity forthree levels of damping;

FIG. 7B graphically illustrates damping force during damping pistontravel within the shock absorber of the present invention; and

FIG. 8 is a cross-sectional view of the alternate preferred shockabsorber having a bypass valve;

FIG. 9 is an exploded isometric view of the bypass housing and valve ofthe shock absorber illustrated in FIG. 8;

FIG. 10A is a cross-sectional view of the bypass shock absorber with thepiston in a partially compression position;

FIG. 10B is a cross-sectional view of the bypass shock absorber in anearly fully compressed position;

FIG. 11A is a partial cross-sectional view of a first alternate bypassvalve arrangement for the shock absorber;

FIG. 11B is a plan view of a portion of the bypass valve arrangement ofFIG. 11A;

FIG. 12A is a partial cross-sectional view of a second alternate bypassvalve arrangement for the shock absorber;

FIG. 12B is a top view of a portion of the valve arrangement of FIG.12A;

FIG. 12C is a top cross-sectional view of a lower portion of the valvearrangement of FIGS. 12A and 12B;

FIG. 13 provides a front plan view of a telescoping front forksuspension assembly incorporating an alternate embodiment of a bypassvalve arrangement of the present invention;

FIG. 14 provides a longitudinal cross sectional view of the bypass valvearrangement taken along line 14--14 of FIG. 13;

FIGS. 15 and 16 provide partial longitudinal cross sectional views ofthe bypass valve and piston areas, respectively, of the bypass valvearrangement of FIG. 13;

FIG. 17 provides a longitudinal cross sectional view of a still furtheralternate embodiment of a bypass valve arrangement of the presentinvention; and

FIGS. 18 and 19 provide partial longitudinal cross sectional views ofthe bypass valve and piston areas, respectively, of the bypass valvearrangement of FIG. 17.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The shock absorber damping system of the present invention may beemployed in a multitude of different applications. However, the systemdisclosed and described herein is particularly well suited to vehicles,especially bicycles of the mountain bike variety. The system is alsowell suited to motorcycle suspension systems, especially off-roadmotorcycles. Mountain bicycles will be referred to throughout thisdetailed description. However, it should be understood that mountainbikes are simply the preferred application and the same concepts andbasic constructions can be used in other shock absorber applications.

The damping system of the present shock absorber is particularlyadvantageous with mountain bikes since large, medium, and small bumps,drops, and shock-producing surfaces are encountered during mountain bikeriding. Typically, low amplitude bumps occur at a high frequency. Forexample, a washboard gravel road may have numerous, close together smallbumps that create high frequency, low amplitude shocks at the wheels ofthe bicycle. Conversely, high amplitude bumps have a relatively lowerfrequency, since the size of the bump itself dictates that the bumps besomewhat spaced apart. A street curb is an example of a high amplitude,low frequency bump. Numerous rocks, bumps, roots, and other obstaclesare encountered when mountain biking off-road. The shock absorber of thepresent invention is designed to handle all these bumps. Further, theshock absorber may also be programmed to reduce other undesirablecycling effects such as pogo action or bobbing, as well as chain-inducedsuspension action.

FIG. 1 illustrates a mountain bike with the shock absorber of thepresent invention. Bicycle 10 includes a frame 12, wheels 14, a frontsuspension 16, and a rear suspension 18.

Front suspension 16 is attached to the head tube portion of frame 12 andincludes forks 20 that extend downwardly from linkages 22 connectingforks 20 to the frame head tube. A front shock absorber 24 is disposedbetween linkages 22 to provide front suspension action. Both shockabsorption and damping are provided by front shock absorber 24, as isdescribed in detail below. Front suspension 16 may have many alternativeconfigurations, such as telescoping forks, other linkage mechanisms, orshock absorbing stems. The same damping concepts discussed herein can beapplied to these other arrangements.

Rear suspension 18 includes a rear swing arm 26 pivotally attached toframe 12 about a pivot 28. A rear shock absorber 30 is also attached atone end to frame 12. Shock stays 32 extend upwardly from the rearwardend of swing arm 26 to the lower end of rear shock absorber 30. Thus,when swing arm 26 pivots upwardly about pivot 28, shock absorber 30 iscompressed such that the rear wheel 14 is allowed to move relative toframe 12 to absorb and dampen shock. Again, alternative rear suspensionsystems can be employed with rear shock absorber 30. Other systems mayinclude unified rear triangles, unified swing arm and chain stayarrangements, and other linkage assemblies. Leverage ratios on the shockabsorber may change, for example, while still using the same coredamping technology. The concepts herein can also be applied to pullshock absorbers. In all of these systems, damping of the suspensionaction is advantageous.

Bicycle 10 also includes a drive system 34. Drive system 34 ispreferably constructed as is known in the art. Drive system 34 includesa chain 36 that extends around chain rings 38 that are attached to frame12 via the bottom bracket. Cranks 40 are also secured to chain rings 38with pedals 42 at the outer ends. Rear sprockets 44 are secured to therear wheel 14 with a rear derailleur 46 for shifting the chain from onesprocket to another. Drive system 34 is relevant to shock absorption,particularly in the arrangement illustrated in FIG. 1, since the upperdrive line of chain 36 extends beneath pivot 28 such that as force isapplied to pedals 42, chain 36 slightly pulls suspension 18 downwardly.This can be advantageous as it helps to increase traction of rear wheel14 on the riding surface. However, if the rider does not have smoothpedaling action, then cyclic forces on chain 36 may cause cyclic bobbingof rear suspension 18 as the bicycle is ridden. As will be explained inmore detail below, the damping system of rear shock absorber 30 can helpeliminate such chain-induced suspension action.

Referring now to FIGS. 2A-C, the details of the inner construction ofshock absorber 30 will now be discussed. Note that while shock absorber30 refers to the shock absorber used with the rear suspension of thebicycle illustrated in FIG. 1, the same or similar shock absorber can beemployed on the front suspension. Externally, shock absorber 30 appearsmuch like standard shock absorbers currently on the market. Many detailsof the shock absorber are much like those manufactured by Noleen Racingof Adelanto, Calif. Shock absorber 30 includes a shaft 48 extending intoa reservoir housing 50. A spring 52 extends along shaft 48 and over aportion of reservoir housing 50. Spring 52 absorbs shock and providesrebound while shaft 48, extending into reservoir housing 50, providesdamping as explained below.

Reservoir housing 50 encloses hydraulic reservoir 54 and gas chamber 56.Hydraulic reservoir 54 is separated from gas chamber 56 by a chamberseal 58. In the preferred embodiment of the invention, both gas chamber56 and hydraulic reservoir 54 are contained within the same cylindricalreservoir housing 50. Chamber seal 58 includes an O-ring to separate gaschamber 56 from hydraulic reservoir 54 and to allow chamber seal 58 tomove within reservoir housing 50 as needed. Gas chamber 56 preferablyholds nitrogen gas such that additional damping is provided when the gasis compressed due to a large shock. Alternatively, a gas chamber may bemounted outside reservoir housing 50 in its own chamber with aninterconnecting channel as is well known in the art.

The outer end of reservoir housing 50 opposite shaft 48 includes ahousing end mount 60 for mounting the end of rear shock absorber 30either to a bicycle frame or to other suspension components. A shaft endmount 62 is provided on the opposite side of shock absorber 30 at theend of shaft 48. Note in FIG. 1 that shaft end mount 62 is mounted toframe 12 while housing end mount 60 is secured to shock stays 32.

Spring 52 is held on shaft 48 and reservoir housing 50 with spring stop64 secured to shaft 48 at the end of shaft end mount 62 and preloadwheel 66 at the opposite end of spring 52. Preload wheel 66 isthreadably engaged on reservoir housing 50. Thus, by turning preloadwheel 66, the preload in spring 52 can be adjusted.

An electronics housing 68 is also provided on shock absorber 30. Housing68 holds the power supply and circuitry, as well as the sensor necessaryto control the damping action of shock absorber 30. Housing 68 issecured to reservoir housing 50 with housing clamp 70 extending aroundthe outside thereof between preload wheel 66 and housing end mount 60.

Hydraulic reservoir 54, when manufactured, includes an opening at onlyone end through which shaft 48 is inserted. A reservoir seal 72(including the seal head, the scraper seal, and the O-ring) extendsaround shaft 48 and is held tightly within the open end of reservoirhousing 50 in order to create an enclosed reservoir 54. A reservoir cap74 is also included on the outside of reservoir seal 72. Reservoir cap74 and reservoir seal 72 ensure that no hydraulic fluid escapes fromhydraulic reservoir 54. O-rings are employed at critical locations toensure adequate sealing. Should shaft 48 extend all the way intoreservoir 54, reservoir cap 74 will abut a bottom out bumper 76 held onshaft 48 adjacent spring stop 54.

As with standard Noleen Racing shock absorbers, an adjustment needle 78is housed within shaft 48, shaft 48 being hollow. Adjustment needle 48regulates the bypass flow of hydraulic fluid within hydraulic reservoirpast the piston 86. An adjustment wheel 80 is provided to moveadjustment needle 78 longitudinally within shaft 48 in a conventionalmanner. An element not included in conventional shock absorbers, wire82, extends from housing 68 through a wire seal 84 in shaft end mount62. Wire 82 then extends through a hollowed central core of adjustmentneedle 78 to near the tip thereof. This wire electrically links theelectronics within housing 68 to the dampener valve for control thereof.Since wire 82 extends out the side of adjustment needle 78, rotation ofadjustment needle 78 must be kept in check. Therefore, pin 96 extendsthrough the side of shaft 48 into a recess in the side of adjustmentneedle 78 such that wire 82 may be properly channeled to the side ofbender 94. As will be explained below, wire 82 actually includesmultiple wires within a tough, flexible housing.

The piston assembly of shock absorber 30 is seen in its assembledconfiguration in FIGS. 2A-C and in an exploded view in FIG. 3A. FIG. 3Billustrates an enlarged view of a piston 86. As seen in FIGS. 2A-C andFIG. 3A, a band 88 constructed of a Teflon material is secured aroundpiston 86. In the preferred embodiment of the invention, shim washers 90are stacked against the innermost end of piston 86 (shim washers 90 areshown all together in FIGS. 2A-C such that they appear to be a singletruncated cone). Shim washers 90 function in a conventional manner toregulate the flow of fluid through piston 86, especially during reboundas shaft 48 moves away from reservoir housing 50. A nut 92 is threadablyengaged on the innermost end of shaft 48 to hold shim washers 90securely against piston 86. Nut 92 thus holds the entire piston assemblyon the end of shaft 48.

A bender 94 is secured on the opposite side of piston 86 from shimwashers 90. Bender 94 will be discussed in more detail below inconnection with FIGS. 4A and 4B. Bender 94 includes piezoelectricmaterial that is connected to wire 82 in order to apply a voltage acrossbender 94. Bender 94 is preferably arranged on the shaft side of piston86 in order to control the compression damping of the piston assemblywhen it travels through reservoir 54.

As seen in FIGS. 2A-C and 3A, bleed spacer 98 is held on the shaft sideof bender 94 and is seated on the shoulder of shaft 48 to hold thepiston assembly between the shoulder of shaft 48 and nut 92. Bleedspacer 98 allows the bypass of fluid flow past adjustment needle 78,allows a conduit through which wire 82 extends to the side of bender 94,and rests on the shoulder of shaft 48 for holding the piston assembly inplace. A flexible top out bumper 100 is force-fit onto shaft 48 belowbleed spacer 98. Top out bumper 100 is useful when shaft 48 is pushedall the way out to the end of its stroke by spring 52 such that bumper100 contacts reservoir seal 72.

In the preferred embodiment of the invention, a sensor assembly isprovided to detect both the displacement of shaft 48 and the pistonassembly relative to the reservoir housing 50 as well as the velocity ofshaft 48 and the piston assembly. In the preferred embodiment of theinvention a giant magnetorestrictive sensor (GMR) is employed. Othersensors may alternatively be used to detect either the displacement orvelocity of shaft 48 relative to housing 50. For example, proximitysensors, variable reluctance sensors, or other magnetic or mechanicalsensors may be used. GMR sensors are also referred to asmagnetoresistive sensors. (Description of such sensors can be found inprior art, such as in U.S. Pat. No. 5,450,009 to Murakami, and inmultiple journal articles. Examples of articles discussing such sensorsinclude "Magnetic Field of Dreams," by John Carey, Business Week, Apr.18, 1994; "The Attractions of Giant Magnetoresistance Sensors" by TedTingey, Electrotechnology, Vol. 7, part 5, pgs. 33-35, October-November1996; and in "High Sensitivity Magnetic Field Sensor Using GMR MaterialsWith Integrated Electronics," by Jay L. Brown, Proc. IEEE InternationalSymposium on Circuits and Systems Vol. 3, pgs. 1864-1867, 1995.) Thesensor and control arrangement preferably employed in the presentinvention includes a magnet 102 secured about nut 92 on the end of thepiston assembly. A sensor 104 is secured within housing 68 adjacentreservoir housing 50 near the closed end thereof. Sensor 104 canalternatively be mounted at the end of housing 50. Sensor 104 isconnected to circuit board 106. Circuit board 106 (or alternatively amicroprocessor chip that includes the microprocessor logic to controlbender 94 based on the detection signal from sensor 104. Circuit board106 is then in turn connected to wire 82 for connection to bender 94.The operation of circuit board 106 will be explained in more detail inconnection with FIG. 6. A battery 108 is also held within electronicshousing 68 in order to provide power to sensor 104 and to bender 94.Preferably, a conventional 9-volt battery is used within electronicshousing 68 to provide the power required for the bender and the sensor.

Referring now to FIG. 3B, further details of the functioning of thepiston and valve assembly will be described. Piston 86 is the typesometimes used with shim washers 90. Piston 86 includes a shaft bore 110that slides over the end of shaft 48 to be held thereon. Shaft bore 110is disposed in the center thereof and is circular in cross-section. Acircumferential recess surrounds the outer curved side of piston 86.Circumferential recess 112 is sized to secure Teflon band 88 therein.The face of piston 86 that is turned toward shaft 48 is illustrated inFIG. 3B. The large openings in piston 86 are the compression flowchannels 114. These channels extend entirely through piston 86 andactually begin within recesses on the opposite side of piston 86 fromthat shown in FIG. 3B. Thus, during compression (when shaft 48 is beingpressed into reservoir 54, see FIG. 2B) fluid easily enters channels 114since the recesses allow the flow to go beneath shim washers 90 intochannels 114. However, bender 94 is secured adjacent the shaft side ofpiston 86 so as to obstruct the flow of fluid through channels 114 attheir exit ends.

By controlling the stiffness or bias of bender 94, the flow throughcompression flow channels 114 (see FIG. 2B) can be effectivelycontrolled to increase or decrease the damping.

Rebound flow channels 116 also extend through piston 86. Note that thesechannels are held within rebound flow recess 118 so that bender 94 doesnot significantly obstruct the flow of fluid back through rebound flowchannels 116 (see FIG. 2C). However, note that the size of thesechannels is somewhat smaller than that of compression flow channels 114such that rebound damping is generally greater than compression damping.The flow through rebound flow channels 116 extend from the face shown inFIG. 3B to the opposite face as the piston assembly moves in thedirection of shaft 48. Flow in this direction is obstructed by shimwashers 90 which are deflected by the flow through rebound flow channels116 and by some flow through compression flow channels 114. Rebound flowrecess 118 not only extends around the entrance of rebound flow channels116, but includes arms that extend between compression flow channels 114such that flow may move around bender 94 for rebound action.

In an alternate embodiment of the invention, shim washers 90 may also bereplaced by a bender such as bender 94 to more completely controlrebound damping, as well as compression damping with the pistonassembly.

In another alternate embodiment of the present invention, the flowchannel or channels are disposed in the side of a modified reservoirhousing. In this embodiment, the bender is positioned to regulate theflow of fluid from one side of the piston to the other through thechannel in the housing as the piston is forced through the reservoir.Control of the bender then affects the level of damping.

Referring now to FIGS. 4A and 4B, the construction of bender 94 will bedescribed. Bender 94 includes a disk 120 preferably constructed of apolyimide material. A Polyimide polymer is preferably used due to itstoughness and electric insulating characteristics. Disk 120 includes acenter aperture 122 which slides over the end of shaft 48 between piston86 and bleed spacer 98. Note that the top of bleed spacer 98 includes asmall cylindrical projection to space the outer portion of disk 120 fromthe remainder of bleed spacer 98 to allow bender 94 to flex downwardlytoward bleed spacer 98.

Within disk 120 a piezoelectric top layer 124 and piezoelectric bottomlayer 126 are held. Top layer 124 and bottom layer 126 are spaced fromone another. Alternative embodiments of the invention include only asingle piezoelectric layer or more than two piezoelectric layers.Piezoelectric layers 124 and 126 are also disk-shaped in parallel planesto one another and parallel to the plane of disk 120. First and secondelectrodes 128 and 130 contact the upper and lower faces of top layer124. Electrodes 128 and 130 are connected to circuit board 106 such thata voltage can be applied across piezoelectric top layer 124. As seen inFIG. 4, first and second connectors 136 and 138 are provided forconnection to wires held within wire 82. Third and fourth electrodes 132and 134 are likewise secured above and below piezoelectric bottom layer126 such that a voltage can be applied thereacross. Note that thirdelectrode 132 is adjacent second electrode 130, but does not come incontact therewith. Thus, voltages may be independently applied acrosstop layer 124 and bottom layer 126. Referring to FIGS. 4A and 4B, thirdand fourth connectors 140 and 142 are coupled to third and fourthelectrodes 132 and 134.

When a voltage is applied across piezoelectric top layer 124, thematerial bends in one direction depending on the polarity of the appliedvoltage. The piezoelectric layer will always be biased to flex such thatthe concave side of the layer is the positive polarity, whereas theconvex side is the negative polarity. Therefore, if a voltage is appliedacross top layer 124 in the same direction as across bottom layer 126,then both piezoelectric layers will bend or at least be biased in thesame direction and bias bender 94 in the same direction. Since bender 94bears against compression flow channels 114 of piston 86, then if firstelectrode 128 and third electrode 132 have the negative polarity as thevoltage is applied across top and bottom layers 124 and 126, the dampingwill be increased since bender 94 will tend to be biased strongly towardpiston 86. Thus, increased damping results since the fluid flow throughcompression flow channels 114 is more highly restricted by bender 94essentially having a higher spring rate under the applied voltage.Alternatively, if first and third electrodes 128 and 132 have thepositive polarity and second and fourth electrodes 130 and 134 have anegative polarity, then bender 94 is biased slightly away fromcompression flow channels 114 to decrease the compression damping aspiston 86 is forced through reservoir 54. With no voltage applied acrosslayers 124 and 126, the normal stiffness of disk 120 then affects theflow with a medium level of damping.

Alternatively, differing levels of damping may be accomplished bychanging the voltage applied across top layer 124 and bottom layer 126rather than simply changing the polarity of the voltage applied. In thepreferred embodiment of the invention, amplifiers increase the voltagefrom the 9-volt battery to 200 volts to be applied across the layers ofpiezoelectric material.

In still other alternative embodiments, a different "bender" may beused. For example, an alternative bender 94' is illustrated in FIG. 5.The bender 94' utilizes alternately shaped electrodes 128', butfunctions similarly to bender 94. All corresponding components of bender94' are numbered the same as for bender 94, but are noted with a prime.As a further example, instead of utilizing a piezoelectric material tomove the bender valve, other primary movers could change the biasingforce of a bender covering a fluid channel. For example, anelectromagnet could be employed to change the force of a bender againsta flow orifice.

Likewise, if shim washers 90 are replaced with a bender valve such ashas been described with regard to bender 94, rebound damping can becontrolled by applying voltage to piezoelectric material within a disk.

FIG. 6 illustrates in a schematic diagram the basic logic to drive thetwo piezoelectric layers 124 and 126 within bender 94. As the shockmoves, the position and velocity sensor 104 sends signals through aninstrumentation amplifier to the microprocessor. The logic in themicroprocessor, at predefined conditions, sends signals to the amplifiersuch that the power is provided through the amplifier across thepiezoelectric top and bottom layers in a desirable fashion to eitherincrease or decrease the damping level by changing the bending bias ofbender 94. The amplifier changes the voltage applied across thepiezoelectric material from 9 volts to preferably 200 volts. While inFIG. 6 piezos A and B are shown connected together, it should be notedthat this is simply a schematic diagram and piezos A and B may beindependently switched on and off of applied voltages across them in onedirection or another. The specific electronics for such a circuit whichwould selectively apply voltages to piezoelectric top and bottom layers124 and 126 may be readily accomplished by those skilled in theelectronics arts. Alternatively, instead of a 9-volt battery, otherbattery or power supplies may be employed. For example, if the presentsystem were employed on a motorcycle, the power supply could come fromthe motorcycle power supply (e.g., battery or magneto).

The damping force versus shaft velocity of the shock absorber for eachof the three basic scenarios of bender 94 is illustrated in FIG. 7A. Theline representing the "MID" damping force is the condition in which novoltage is applied across top and bottom layers 124 and 126 of thepiezoelectric material. In this condition, bender 94 acts much like ametal shim that is deflected away from the flow through piston 86 aspiston 86 is forced through hydraulic reservoir 54. With an increase inshaft velocity, the damping force naturally increases. However, if avoltage is applied across piezoelectric top and bottom layers 124 and126 such that the negative polarity is applied to the first and thirdelectrodes 128 and 132, a condition of maximum damping is achieved suchthat the damping follows the "MAX" curve shown in FIG. 7A. However, ifthe polarity is reversed such that bender 94 is biased away from piston86, the damping force follows the "MIN" curve illustrated in FIG. 7A.Thus, without changing the amount of applied voltage, but just bychanging the polarity of the voltage or whether the voltage is appliedat all, three discreet levels of damping can be achieved. In each ofthese levels the damping increases with shaft velocity.

The "MID" level of damping is constructed so that the bender reacts thesame as a current dampener piston assembly with shims being used insteadof bender 94 such that if no power is applied to the piezoelectriclayers, then the shock absorbers still provide good shock performance.This would be the case, for example, if the battery were dead or in caseof some other electrical breakdown.

Referring now to FIG. 7B, a preferred programming of the dampener willbe described. With a rider's weight on bicycle 10, shock absorber 30will move to about 20% of travel. At this point, the compression dampingwill be at the nominal level (MID curve of FIG. 7A) to provideresistance to pogo action of the suspension system due to rider bobbingor chain-induced suspension action. Alternatively, maximum damping maybe applied at this point to further reduce pogo action. However,preferably the MID level of damping is provided until approximately 25%of the travel.

As soon as the shaft moves beyond the 25% point, the system switches tominimum damping by applying the proper voltage with the proper polarityacross piezoelectric layers 124 and 126. Thus, when the rider encounterslow amplitude, high frequency shock, the damping is at a minimum levelto be able to respond quickly to the shock and absorb it without theshock being transferred to the rider through the bike frame 12.

If the shaft goes past 50% of travel, its velocity is computed by thesensor and chip. If the velocity is greater than about 30 inches persecond the system switches to the MID level of damping. This would bethe case when a larger bump is encountered. If the velocity of the shaftis greater than 60 inches per second, the damping would switch directlyto the MAX damping level to deal with extremely large bumps. At 70% oftravel, the shaft velocity will be recomputed and, if greater than 30inches per second and not already in the stiff MAX level, then it wouldbe switched to that level. Thus, the system will avoid the suspensioncompletely bottoming out by providing increased compression damping tohandle the large shocks.

When the shaft returns to a position less than 50% of travel, the systemswitches to the MID stiffness level, if it is not already there. Theabove is just one possible scenario that may be programmed into thelogic circuit in the circuit board or chip such that the suspensiondamping actively and instantaneously responds to shocks encountered. Thefigures above for velocity and displacement are simply one set thatcould be used. Depending on how the shock is arranged with a givensuspension system and the desired attributes of the shock, these numberscan be changed and the chip or circuit board can be programmedaccordingly.

Thus, the level of damping is automatically and instantaneously changedduring riding so that low amplitude, high frequency bumps are easilyabsorbed with minimal damping while large high amplitude low frequencybumps are absorbed with higher damping so as to not bottom out thesuspension and to avoid the shock from springing back too quickly. Bothvelocity and displacement of the shaft relative to the reservoir housing50 are important to proper damping. If the travel passes 50%, but thevelocity is very slow, then increased damping is not required. However,if the travel passes 50% with a very high velocity, then increaseddamping can be effective in improved shock absorber performance.Nevertheless, alternative embodiments may also be employed wherevelocity by itself or displacement by itself are measured and thedamping level is adjusted based on a single input. Further, other sensorinput may also be employed to control damping levels.

Referring now to FIGS. 8-12, a preferred embodiment of a bypass valvearrangement of the present invention will now be described along withtwo alternate embodiments of the bypass valve arrangement. The bypassvalve utilizes many of the same concepts and features discussed above,especially in the preferred embodiment. Thus, the above discussion ofthe operation of the electronic circuitry to increase or decrease thedamping forces during certain portions of the stroke of the piston ortravel of the suspension substantially applies to the embodimentsdiscussed below. Furthermore, the advantages discussed above also applyto these embodiments. The last two digits of the numbering is the sameas above for similar or identical elements designated below.

The bypass valve preferred embodiment of the invention will now bediscussed with FIGS. 8-10. The bypass valve functions with a shockabsorber arrangement very similar to that discussed above in that theshock absorber includes a shaft 148 having a spring 152 thereabout, theshaft connected to a piston 186 that is slidably disposed within ahydraulic reservoir 154. Hydraulic reservoir 154 is formed with areservoir housing 150. In this particular embodiment of this invention,reservoir housing 150 includes a housing flange 249 to secure the bypassvalve arrangement.

Piston 186 may include piezo disks at the end thereof to control theflow through piston 186 as described above. However, in the preferredembodiment of the shock absorber 130 with the bypass valve arrangement,conventional rebound shim washers 190 and compression shim washers 191are employed against the forward and trailing sides of piston 186.Piston 186 includes a magnet 202 secured about nut 192 to provide apreferred method of sensing the position and displacement of piston 186relative to housing 150 in combination with a sensor 104 secured nearthe housing end mount 160 of shock absorber 130 as described above. Shimwashers 190 and 191 are preferably a stack of thin metallic washers thatcan be arranged and adjusted to preset characteristics for compressionand rebound damping. With the bypass valve arrangement, shim washers 190and 191 may be arranged and constructed such that higher damping throughpiston 186 is achieved due to the extra damping allowed through thebypass valve assembly as described below.

The bypass valve assembly is best illustrated in FIGS. 8 and 9.Reservoir housing 150 is specially constructed so as to include housingflange 249 to secure the elements of the bypass valve assembly.Reservoir housing 150 includes the standard housing to create hydraulicreservoir 154. Within the sides of reservoir housing 150 inflow openings256 and outflow channel 276 extend therethrough into inflow chamber 258.Orifice plate 254 separates inflow chamber 258 from outflow channel 276.Orifice plate 254 covers inflow openings 256 and channels the fluid thatenters inflow openings 256 to an orifice 260. Orifice plate 254 has agenerally parallelepiped outer shape with a lower recess to form inflowchamber 258 between orifice plate 254 and reservoir housing 150. Orifice260 is a slot with upwardly projecting lips within one end of orificeplate 254. The lips extend upwardly from the upper surface of orificeplate 254.

Bender 252 is seated on top of orifice plate 254. The lower surface ofbender 252 is protected with a valve shim 264. Bender 252 is generallyrectangular in shape and includes a layered construction such as thatdescribed above for use with the piezo disk embodiment. Bender 252includes a bender cable 266 that extends upwardly from the rearward endof bender 252 to provide electrical interconnections in order to applyvoltages across the various layers of bender 252. Valve shim 264 ispreferably constructed of a brass material and is secured to therearward ends of both orifice plate 254 and bender 252. Valve shim 264is generally coextensive with the bottom surface of bender 252 toprotect the bottom surface thereof. Valve shim 264 is thus sandwichedbetween bender 252 and orifice plate 254 and rests immediately on top ofthe lips of orifice 260 to restrict the flow thereof with bender 252.Bender 252 may alternatively be comprised of another response materialthat may be variably biased based on magnetic or electrical or otherforces. Alternatively, bender 252 may simply be a passive bender, suchas spring steel, to simply have a constant spring rate or variablespring rate depending on the stacking of shims, for example, to affectthe flow through orifice 260. A bender clamp 268 with screws secures thebender, valve shim, and orifice plate assembly to the top of reservoirhousing 150.

A substantially rectangular bypass cover 250 with a recess in the lowerside thereof is secured to housing flange 249 to secure the entire valveassembly in place. Bypass cover 250 includes cable opening 269 to allowbender cable 266 to project therethrough for interconnection with a wireribbon 274 leading to the electronics circuit board within electronicshousing 168 as described above. The cable O-ring 270 and cable sealclamp 272 secure to the top of cable opening 269 to seal bender cable266 such that no fluid escapes bypass cover 250. Electronics housing 168covers the top of bypass cover 250 and includes the circuit board,battery, and wire ribbon to control the biasing of bender 252 toactively control the flow through the bypass valve assembly; theelectronics may activate the bender, as described above with regard tothe disk-shaped bender. Thus, the biasing force supplied by bender 252onto orifice 260 may be varied based on input received from sensor 204and transmitted to the circuit board.

Referring now to FIGS. 8, 10A and 10B, the basic functioning of thebypass valve assembly will now be described. Shock absorber 130illustrated in FIG. 8 is in an initial position before being compressedeither by rider weight or by forces acting on shock absorber 130, suchas bumps or other shocks to the bicycle or other apparatus to whichshock absorber 130 is secured. The following description will refer toshock absorber 130 for use in its preferred application on a mountainbike. However, it should be understood that shock absorber 130 could beused for other articles, including other vehicles, machines, or otherdevices.

In the initial position illustrated in FIG. 8, note that piston 186 isbelow both inflow openings 256 and outflow channel 276 such thatcompression of piston 186 within hydraulic reservoir 154 will not yieldany bypass flow. Thus, the initial stroke of piston 186 is somewhatstiff due to not having this extra damping action. This is desirable atthe beginning of the stroke to decrease rider- or pedal-inducedsuspension action on a mountain bike. This also is the general region inwhich the preload from the weight of the rider will act on shockabsorber 130. Thus, it is desirable that shock absorber 130 not compressexcessively under the preload of the rider, but retain most of itssuspension action for actual shocks encountered while riding. Alternateembodiments of the invention, wherein initial soft damping is required,may include outflow channel 276 extending below piston 186 when in theno-stroke position illustrated in FIG. 8. Note in this position that asforce is applied to compress piston 186 within reservoir 154 that thepressures will be balanced and no substantial flow through the bypassvalve assembly will occur. The only flow from one side of piston 186 tothe other must occur through piston 186 itself. If no flow channels areprovided in piston 186, movement could still be allowed due to thecompression of the gas within gas chamber 156. This would be the case ifparticularly stiff damping is desired during the initial portion of thestroke of shock absorber 130.

FIG. 10A illustrates an intermediate stroke position of piston 186within reservoir 154. In this position, piston 186 is beyond outflowchannel 276 such that flow through the bypass valve assembly is allowed;as piston 186 pushes further within reservoir 154, fluid is forcedthrough inflow openings 256 into inflow chamber 258. From inflow chamber258, fluid proceeds to orifice 260 and is forced against the lower sideof valve shim 264 held in place by bender 252. Note that bender 252 isbiased against orifice 260 as controlled by the logic circuit of thecircuit board housed within electronics housing 168 as described above.Alternatively, the variable biasing of bender 252 may be turned off suchthat the natural spring resilience of bender 252 simply operates in aconstant bias against orifice 260 to control the flow. In anotheralternate embodiment of the electronics, bender 252 may be biased to aset condition by applying a constant voltage to the piezoelectricmaterial sandwiched within bender 252. In any event, as the pressure ofthe fluid bears sufficiently against bender 252, the fluid passesbetween the orifice 260 and bender valve shim 264 to enter outflowchannel 276 and fill in behind piston 186. Note that this region ofpiston 186 compression may be the lowest damping force in this preferredembodiment since flow is allowed through all of inflow openings 256(preferably five) and out of outflow channel 276 to the back side ofpiston 186.

In the position of piston 186 illustrated in FIG. 10B, the flow throughthe bypass valve assembly is again somewhat restricted. This is due tothe sides of piston 186 initially blocking the first holes of inflowopenings 256 and then blocking all of inflow openings 256 such that noflow extends through the bypass valve assembly. Thus, shock absorber 130becomes much stiffer. This can be very advantageous to avoid bottomingout shock absorber 130 during a heavy shock event. By having inflowopenings 256 sequentially covered, the damping force increases thecloser piston and shock absorber 130 come to bottoming out. Thus, threeinflow openings 256 are first covered and then two additional openingsare covered before flow is entirely stopped through the bypass valveassembly.

Thus, even without electronic or other control of bender 252,significant advantageous properties of damping are achieved with thebypass valve arrangement illustrated and described above. The damping ishigher at the initial portion of the stroke to deal with rider preload,as well as pedal- or rider-induced bobbing, and eliminate these negativeeffects on the shock absorber. As actual bumps are encountered, thedamping goes to a moderate to low level to allow the shock absorber 130to absorb the shock effectively. When large bumps are encountered, thedamping progressively increases as the stroke increases to cover inflowopenings 256. By further including an active piezo bender 252 combinedwith a sensor 204, the velocity of piston 186 can also be taken intoaccount in addition to the displacement to change the damping force toan optimum level for the smoothest ride possible with the bestconnection of the wheels to the ground. The arrangement is alsoadvantageous should the electronics or wiring fail in the piezoelectricembodiment; the shock absorber would still work better than standardshock absorbers if a given spring constant is inherent in bender 252 toprovide damping by having a constant biasing force against orifice 260.

An alternate embodiment of the bypass valve assembly will now bedescribed in connection with FIGS. 11A and 11B. In this embodiment, avalve body 378 is provided and moved by piezo bender 352. The valve bodyitself is balanced with respect to the fluid forces flowing through thebypass valve assembly such that piezo bender 352 does not have to bearas much against the full pressure of the flow of the fluid through thebypass valve assembly. During compression of the piston, flow entersinflow openings 356 and pushes upwardly on a flapper valve 388. Flappervalve 388 is preferably a thin sheet of stainless steel that may beeasily bent upwardly by the pressure of the fluid flowing through inflowopenings 356. Flapper valve 388 obstructs flow going in the oppositedirection such that flow will not exit inflow openings 356. Fluid thenenters inflow chamber 358 which is beneath and surrounds bender 352.Bender 352 is secured to chamber plate 354 with a bender clamp 368secured to the bottom thereof. Thus, bender 352 is secured to theunderside of chamber plate 354. The sides of chamber plate 354 arenarrower than inflow chamber 358 such that flow is allowed to move abovechamber plate 354 into upper channel 380 that extends to valve body 378.Valve body 378 is generally cylindrical in shape and moves in adirection transverse to the longitudinal axis of the shock absorber andtransverse the longitudinal axis of bender 352. Thus, bender 352 movesup and down with valve body 378 without valve body 378 moving in adirection opposite the flow of fluid through the bypass valve assembly.Valve body 378 includes a valve recess at a lower portion thereof on theside of valve body 378 abutting bender 352. The end of bender 352extends within valve recess 384. A bender clip 369 is secured to the endof rectangular-shaped bender 352 to engage within valve recess 384.Bender clip 369 is preferably C-shaped in cross-section and its innerportion is secured to the distal end of bender 352. The outer corner ofbender clip 369 bears against the sides of valve recess 384 such thatwhen piezo bender 352 is biased upwardly or downwardly due to an appliedvoltage across the layers thereof (as discussed above), bender clip 369will push valve body 378 upwardly or downwardly to restrict or allowflow over the top of valve body 378. Valve body 378 includes a hollowcore 382 such that valve body 378 is balanced. In other words, thepressure of the hydraulic fluid will not have as much effect on theposition of valve body 378 since fluid is allowed to flow entirelythrough valve body 378. In order for flow to exit the bypass valve, andvalve body 378 in particular, it must pass over the rim of valve body378 into side channels 386. FIG. 11B, illustrates flow over the top ofvalve body 378 into side channels 386 such that the flow can exitthrough outflow channel 376. The upper rim of valve body 378 is angledto further decrease the effect of the flow on biasing valve body 378downwardly. Thus, with a substantially balanced valve body 378, thepower requirements to move bender 352 are much lower. The embodimentdescribed and illustrated in FIGS. 11A and 11B otherwise functions muchthe same as the preferred bypass valve arrangement described above withinflow openings 356 and outflow channel 376 positioned accordingly.

A second alternate embodiment with a balance valve body will now bedescribed in connection with FIGS. 12A-12C. In this embodiment, a valvebody 478 is provided that is also balanced somewhat to avoid the effectof the direct force of the fluid flowing through the bypass valvearrangement pushing the valve body 478 away from flow restriction andthus requiring less power. The embodiment illustrated in FIGS. 12A-12Cmay require even less power than other embodiments due to itsarrangement of secondary flow moving valve body 478 with a diaphragm504. A bender 452 is provided clamped within a chamber plate 454 in amanner similar to that described above in connection with FIGS. 11A andB. However, bender 452 does not extend to a direct connection with valvebody 478. Bender 452 secures to chamber plate 454 with bender clamp 468,but extends toward valve body 478 only enough to cover a secondary floworifice 460. Secondary flow orifice 460 provides a small openingadjacent cylindrical valve body 478, which allows a moderate flow offluid to extend upwardly and be channeled into a secondary flow channel490. Secondary flow channel 490 channels the secondary flow to the sideof chamber plate 454 and then upwardly such that it may enter into adiaphragm chamber 492 disposed above cylindrical diaphragm 504.Diaphragm 504 is cylindrical in shape and is sealed to chamber plate 454with seals 506 directly above valve body 478. Valve body 478 iscylindrical in shape and has a hollow core 482. Valve body 478 alsoincludes a valve stem 494 projecting upwardly from the center thereof toengage the center of diaphragm 504. Diaphragm 504 is constructed of athin elastically flexing material. Thus, when diaphragm 504 movesupwardly or downwardly, it moves valve body 478 upwardly or downwardlyaccordingly. A balance chamber 480 is provided below diaphragm 504 toallow for movement of diaphragm 504 and to balance the fluid forces onvalve body 478 such that it can move transverse to the general primaryflow of fluid through the bypass valve assembly. The primary flowproceeds through inflow openings 456 beneath flapper valve 488 and theninto side channels 486. Side channels 486 are illustrated in FIG. 12Cand extend from the side of a lower plate 500 beneath valve body 478 tothe sides of valve body 478. The exit of flow is allowed through theside of valve body 478, which includes a flow recess 498 to allow theflow to exit into outflow channel 476. Note that a balance orifice 496extends through the top of valve body 478 to allow fluid to enterbalance chamber 480 such that the pressure of the primary flow does notpress valve body 478 upwardly and thus provides no valve action. Thesecondary flow that extends through or past bender 452, throughsecondary flow orifice 460, and secondary flow channel 490 and intodiaphragm chamber 492, is allowed to exit diaphragm chamber 492 througha bleed channel 502. Bleed channel 502 is situated to the side ofdiaphragm 504 within chamber plate 454. Bleed channel 502 allows theflow to exit into outflow channel 476. The bypass valve assemblyoperates by controlling the amount of fluid allowed into and overdiaphragm chamber 492, thus affecting the flex of diaphragm 502.Diaphragm 502 adjusts the position of valve body 478 upwardly ordownwardly to cut-off the primary flow of fluid past valve body 478. Theprimary flow is cut-off when valve body 478 is pushed downwardly, thusrestricting the flow through side channels 486. This embodiment isadvantageous because less power is needed to move bender 452 since onlya secondary flow must be controlled by bender 452.

FIG. 12B illustrates the flow of the secondary fluid. FIG. 12Billustrates the arrangement with bypass cover 450 removed. FIG. 12C isan illustration with a cross-section in a position as shown in FIG. 12A.

Attention is now directed to FIGS. 13-19, which illustrate twoadditional alternate preferred embodiments of a bypass valve arrangementof the present invention in which a fluid and piston dampener,piezoelectric bypass valve and bypass flow channels, and associatedelectronic circuitry and power supply are arranged longitudinally withina telescoping suspension strut including a stanchion tube and a slidetube. The bypass valve arrangements of the embodiments of FIGS. 13-19share many features in common with the previously discussed embodiments,in particular the embodiments of FIGS. 8 and 11. The discussion aboveregarding operation of the present invention, and in particular theaction of electronic circuitry to increase or decrease damping forcesduring certain portions of the compression and rebound strokes of thepiston apply equally to the embodiments discussed below, and thus arenot repeated to avoid redundancy. Further, those elements of theembodiments illustrated in FIGS. 13-19 that function identically orsubstantially the same as corresponding features or elements of thepreviously described embodiments are referred to by the same descriptor,and a detailed description of these is again not repeated to avoidredundancy.

Referring to FIG. 13, a front fork and suspension assembly 610 isillustrated. The front fork and suspension assembly 610 includes a stem612 that has an upper end receivable within a frame head tube (notshown) and a lower end that supports vertically spaced upper and lowerbridge members 614. Each bridge member 614 has a yoke shapedconfiguration and includes an aperture on either side that receives andis secured to downwardly depending stanchion tubes 616 and 617. Eachstanchion tube 616, 617 slidably receives on the exterior of its lowerend a slide tube 618. Each slidably coupled stanchion tube 616, 617 andassociated slide tube 618 forms one of the telescoping front forks of abicycle frame. The upper ends of the slide tubes 618 are securedtogether by another bridge member 620, which is configured in the shapeof a downturned U, and each end of which defines a clamp secured aboutthe corresponding slide tube 618. A hub dropout 622 is formed on thelower end of each slide tube 618 for purposes of detachably mounting thehub of a wheel.

In the preferred embodiment of FIG. 13, a spring pack and a dampener aremounted separately within the first and second stanchion tubes 616, 617.Thus the first stanchion tube 616 carries a dampener (FIG. 14), whilethe second stanchion tube 617 carries a spring 624 that rides on a shaft626. The shaft 626 can be secured to either the stanchion tube 617 orthe corresponding slide tube 618, and the spring 624 is compressedbetween stops (not shown). The spring 624 may be alternately mounted,such as without a shaft 626, or on the outside of the stanchion tube617. The spring 624 provides shock absorption which is dampened by adampener (FIG. 14) received within the opposite stanchion tube 616, asshall be described with reference to FIGS. 14-16, and also providesrebound force for the dampener. The two stanchion tubes 616 are rigidlycoupled by the bridge members 614, and are further stabilized by thebridge member 620 that rigidly couples the slide tubes 618, such thatbalanced shock absorption and dampening occurs. While the preferredembodiment illustrates a spring mounted on a first stanchion tube and adampener mounted on a second stanchion tube, it should be apparent thatthe present invention is well suited for other arrangements, such as aspring and dampener mounted within each stanchion tube, or a spring anddampener combination mounted in only one stanchion tube. Further, thespring could be mounted in the slide tube 618 associated with thestanchion tube 616. Likewise, while the front fork and suspensionassembly 610 illustrated in FIG. 13 is for the front suspension of abicycle, the dampener embodiments illustrated in FIGS. 14-19 for usetherein should be understood to be equally well suited for use in rearsuspensions, and for other vehicles, such as motorcycles.

Referring to FIG. 14, all components of the dampener 628 of theembodiment of FIG. 13 are mounted within the stanchion tube 616 andcorresponding slide tube 618. The components are mounted linearly alonga common longitudinal axis of the stanchion tube 616 and slide tube 618.The inner surface of the upper end of the slide tube 618 slidablyreceives the lower end portion 630 of the stanchion tube 616. An annularseal assembly 632 is mounted within the upper end of the slide tube 618to prevent debris from lodging therebetween, and includes an oil seal634 and scraper seal 636, as shown in FIG. 15. Additional annularbushings 638 are received between mating surfaces of the lower endportion 630 and the slide tube 618, as shown in FIGS. 15 and 16.

Referring to FIGS. 14-16, a tubular hydraulic fluid sleeve 640 isclosely and coaxially received within the lower end portion 630 of thestanchion tube 616. The hydraulic fluid sleeve 640 is secured, such asby a threaded engagement or spring clip, or otherwise secured so thatits longitudinal position within the stanchion tubes 616 is fixed. Firstand second annular seals 642, such as O-ring seals, are mounted on theexterior of the lower end, and adjacent the upper end, of the hydraulicfluid sleeve 640, and create a seal against the inner surface of thelower end portion 630 of the stanchion tube 616. The outer surface ofthe hydraulic fluid sleeve 640 is machined, cast or otherwise formed todefine a reduced diameter portion 644 between the annular seals 642. Anannular space is thus defined between the exterior of the hydraulicfluid sleeve 640 and the interior of the lower end portion 630 of thestanchion tube 616, to form a bypass flow channel 646, the purpose ofwhich will be described subsequently. The bypass flow channel 646extends longitudinally, surrounds the hydraulic fluid sleeve 640, andextends the majority of the length of the hydraulic fluid sleeve 640between the annular seals 642.

The interior of the hydraulic fluid sleeve 640 defines a hydraulicchamber 648 and a gas chamber 650, which are separated by alongitudinally floating chamber seal 652. In the preferred embodiment,the hydraulic chamber 648 receives a first fluid, preferably a hydraulicoil, while the gas chamber 650 receives a second, compressible fluid,such as nitrogen gas, air or other inert gas. The chamber seal 652sealingly engages with the interior of the hydraulic sleeve 640, andslides upwardly or downwardly depending on pressure differentialsexerted thereon.

A piston shaft 654 is secured to the bottom of the interior of the slidetube 618, and projects centrally and upwardly therefrom. The pistonshaft 654 carries on its upper end a piston assembly 656, which isslidably received within the hydraulic chamber 648 in the interior ofthe hydraulic fluid sleeve 640. The piston shaft 654 and the pistonassembly 656 are suitably constructed identically to the previouslydescribed piston 186 and shaft 148 of the embodiment of FIG. 8, exceptthat a magnet is not mounted on the piston, being mounted elsewhere asdescribed below. Thus briefly the piston shaft 654 includes an internaladjustment rod 658, adjustable by either disassembling the slide tubeand stanchion tube, or alternately by adjusting an externally mountedadjuster such as a hexagonally keyed activator (not shown) extendingfrom the lower end of the slide tube. The piston assembly 656 includes apiston 660 including longitudinal compression passages 662 and reboundpassages (not shown), flow through which is modulated by compressionshim washers 664 and rebound shim washers 666, respectively, all ofwhich are retained by an axially secured nut 668. The flow of fluid fromone side to the other of the piston 660 on the compression and reboundstrokes is dampened by fluid flow restrictions through the compressionand rebound passages, as modulated by the shim washers.

Additional adjustable dampening is provided by way of a responsivebypass valve 670, best illustrated in FIG. 15. A cylindrical valveplatform 672 is secured within a recessed upper portion of the upper endof the hydraulic fluid sleeve 640. The valve platform 672 is secured inposition by a spring clip 674, and is sealed at each end by first andsecond seals 676, such as O-ring seals, received on the exterior surfaceof the valve platform 672. The valve platform 672 is thus longitudinallyaligned on the common longitudinal axis of the stanchion tube 616, andis disposed approximately midway within the length of the stanchion tube616. One radial side of the valve platform 672 is recessed between theseals 676 to enable mounting of the remaining components of theresponsive valve assembly 670. A longitudinally extending inlet bore 678extends from a lower face of the valve platform 672, along an axis thatis parallel to but offset from the central axis of the valve platform672, approximately halfway into the length of the valve platform 672.The inlet bore 678 is offset on the opposite side of the recessedportion of the valve platform 672. A radial bore 680 is formedtransversely through the valve platform 672, from the recessed side toconnect with the upper end of the inlet bore 678. The inlet bore 678 andradial bore 680 thus define a fluid flow path from the lower surface ofthe valve platform 672 to the recessed side of the valve platform 672.

Referring still to FIG. 15, the chamber seal 652 includes on its lowerside a central recess 682. A longitudinal aperture is formed through theremaining portion of the chamber seal 652, extending from the bottom ofthe recess 682 to the upper surface of the chamber seal 652, along anaxis that is offset radially from the longitudinal axis of the chamberseal 652 and which is aligned with a longitudinal axis of the inlet bore678 within the valve platform 672. An extension tube 684 has a lower endthat is press fit or otherwise secured within this aperture of thechamber seal 652, and an upper end that is slidably received within thelongitudinal inlet bore 678 of the valve platform 672. The extensiontube 684 thus passes completely through the nitrogen gas chamber 650. Anannular seal 686 is disposed within an annular recess formed about thelower end of the longitudinal inlet bore 678, to create a gas tightslidable seal with the extension tube 684. As the chamber seal 652floats upwardly and downwardly during compression and decompression ofthe nitrogen gas within the gas chamber 650, the extension tube 684remains in sliding sealed engagement within the inlet bore 678 of thevalve platform 672. The extension tube 684 defines a hydraulic fluidflow path from the hydraulic chamber 648, through the chamber seal 652and through the extension tube 684, into the inlet bore 678 of the valveplatform 672. This arrangement thus provides for longitudinal passage ofhydraulic fluid through the gas chamber 650 to the responsive valveassembly 670 without commingling of hydraulic fluid and gas.

A longitudinal valve plate 688 is secured to the recessed side of thevalve platform 672. The valve plate 688 has a recessed inner surfacethat cooperatively defines a cavity 690 with the recess surface of thevalve platform 672, into which the radial bore 680 opens. The cavity 690is bordered by a rim defined on the inside of the valve plate 688, whichcompresses a gasket against the valve plateform 672. The gasket includesa flap like extension that overlies the radial bore 680, and serves as aone way valve, which prevents backflow through the radial bore 680. Thevalve plate 688 also includes an annular valve guide 692 that projectsradially outward from a lower portion of the valve plate 688, and whichis oriented orthogonally to the longitudinal axis of the hydraulic fluidsleeve 640. The interior of the annular valve guide 692 slidably andclosely receives a hollow cylindrical valve member 694. The valve member694 has a relatively thin tubular wall. The inner facing end of thecylindrical valve member 694 is internally chamfered, presenting aknife-like edge that selectively abuts the recessed surface of the valveplatform 672. When the valve member 694 is in a position such that itabuts the valve platform 672, the valve member 694 blocks the flow ofhydraulic fluid, which enters through the inlet bore 678 into the cavity690, from passing through the valve plate 688. However, when the valvemember 694 is deflected radially outward, away from the valve platform672 as shall be subsequently described, a space is created between thevalve member 694 and the recessed surface of the valve platform 672, asillustrated in FIG. 15. Hydraulic fluid can then flow from the cavity690 and pass through the hollow interior of the valve member 694,flowing into a chamber 696 defined between the recessed side of thevalve platform 672 and the inner wall of the hydraulic fluid sleeve 640.

A radial aperture 698 is defined in the wall of the hydraulic fluidsleeve 640, below the uppermost seal 642, and provides a fluid path fromthe chamber 696 to the bypass flow channel 646 defined between thehydraulic fluid sleeve 640 and the interior of the extension tube 616.Thus, depending on the positioning of the valve member 694, hydraulicfluid can be selectively permitted to flow from the hydraulic chamber648, through the extension tube 684, through the passages formed withinthe valve platform 672, through the thusly positioned valve member 694,out through the cavity 690 and aperture 698, and into the bypass flowchannel 646, as indicated by the directional flow arrows shown in FIG.15. The hydraulic fluid then flows downwardly around the outer reduceddiameter surface 644 of the hydraulic fluid sleeve 640 along the bypassflow channel 646.

Referring to FIG. 16, at the lowermost extremity of the bypass flowchannel 646, several return apertures 700 are formed radially throughthe lower portion of the hydraulic fluid sleeve 640, above the annularseal 642. Hydraulic fluid thus passes from the bypass flow channel 646,through the return apertures 700, and into the hydraulic chamber 648 onthe backside, i.e., lowermost side of the piston 660. This thuscompletes bypass flow of hydraulic fluid around the piston 660 when alesser degree of dampening is desired. This return flow is indicated bythe directional flow arrows shown in FIG. 16.

Referring still to FIGS. 15 and 16, positioning of the valve member 694,and thus control of hydraulic fluid through the bypass flow channel 646,is controlled by a responsive valve component. In the preferredembodiment of FIG. 15, the responsive valve component is a piezoelectricbender 702. The piezoelectric bender 702 is constructed and operatessimilarly to the bender 252 of the previously described embodiment ofFIG. 8. Referring still to FIG. 15, the bender 702 is mounted by a clamp704 secured by a bolt or other fastener to the uppermost end of thevalve plate 688. The bender 702 thus extends downwardly and parallel tothe valve plate 688, and is oriented parallel to the longitudinal axisof the stanchion tube 616. The piezoelectric bender 702 has a width thatis slightly less than that of the valve plate 688. A longitudinal recessis formed across the width of the outer surface of the valve plate 688,between the clamp 704 and the annular valve guide 692, such that thebender 702 in this region is spaced apart from the outer surface of thevalve plate 688. This thus permits hydraulic fluid within the chamber696 to surround all sides of the bender 702, preventing differentialfluid pressure from being inserted thereon.

The lowermost tip of the bender 702 is engaged with the valve member694. Specifically, an aperture 706 is defined through the side of thevalve guide 692 facing the bender 702. The valve member 694 includes aslot like internally projecting recess 708 in the sidewall thereof,again facing towards the bender 702. The bender 702 extends through theaperture 706 of the valve guide 692, and is received within the recess708 of the valve member 694. The aperture 706 is wider than the width ofthe bender 702 such that the bender 702 can move inwardly and outwardly,i.e., in a direction transverse to its length, within the aperture 706.When power is provided to the bender 702 to cause it to flex, in themanner previously described with regard to earlier embodiments, thevalve member 694 is caused to move along its longitudinal axis, i.e.,orthogonally relative to the longitudinal axis of the stanchion tube616. This flexure of the bender 702 thus can move the valve member 694selectively between a closed position in which the valve member 694 isbiased against the valve platform 672, and an open position, as shown inFIG. 15, in which the valve member 694 is spaced away from the valveplatform 672 to permit hydraulic fluid flow therethrough for bypassflow.

Attention is now directed to FIGS. 14 and 15 to describe the mounting ofadditional components involved in activation of the bender 702. Thestanchion tube 616 includes a plurality of cross braces 710 secured atspaced intervals across the width of the interior of the stanchion tube616, above the valve platform 672. A circuit board 712 on whichcircuitry required to activate the bender 702 is mounted, is secured tothe lowermost and intermediate cross braces 710. A tubular wire guide714 is secured to the underside of the lowermost cross brace 710, andprojects downwardly therefrom. Power leads from the circuit board 712extend through the wire guides 714, through an aperture 716 formedthrough the upper end of the valve platform 672, and are connected tothe bender 702 adjacent the clamp 704. As in previously describedembodiments, the bender 702 is preferably activated in response toeither or both of the distance of travel of the piston 660 duringcompression and rebound of the suspension system, or the velocity ofpiston 660 travel. To permit sensing of the distance and velocity, thedampener includes a magnet 718 mounted adjacent the upper end of thehydraulic chamber 648 within the bridge member 620, and a sensor 720mounted a longitudinal distance spaced therefrom on the lowermost crossbrace 710.

The stanchion tube 616 further provides housing for a power supply suchas a battery 722 housed within a battery chamber formed in the upper endof the stanchion tube 616 between the uppermost cross base 710 and athreaded cap 724 secured to the upper end of the stanchion tube 616. Thecap 724 permits access to and replacement of the battery 722. Powerleads (not shown) extend from the positive and negative poles of thebattery 722 to the circuit board 712.

Thus, all components of the dampener 628 are housed within thetelescoping stanchion tube 616 and slide tube 618, in longitudinallinear array fashion. Alternately, the electronics could be mountedwithin a recess of the valve platform. As the telescoping strut formedby the stanchion tube 616 and slide tube 618 compresses, dampening isprovided both by the hydraulic fluid in the hydraulic chamber 648.Compression of gas within the gas chamber 650 accommodates for a changein fluid chamber volume. The extent of dampening is automaticallyadjusted during compression and rebound for high frequency or lowfrequency dampening, by activation of the bender 702 to permit, block ormodulate bypass hydraulic fluid flow through the responsive valveassembly 670.

Various modifications can be made to the dampener arrangement 628illustrated in FIGS. 14 through 16, such as those previously describedwith regard to other embodiments. Thus, other electrical and mechanicalsensors can be utilized to activate the responsive valve assembly 670.Other arrangements of benders, such as piston mounted benders andflap-type benders, such as those described in previous embodiments,could also be incorporated into a telescoping suspension in accordancewith the present invention.

One such additional alternative for a telescoping suspension withresponsive bypass dampening is illustrated in FIGS. 17 through 19. FIG.17 illustrates a dampener 730 that is similar in many regards to thepreviously described dampener 628, except that it includes chambers foronly a first fluid, e.g., gas or oil, preferably a compressible gas, andincludes no hydraulic sleeve, with all components instead being directlymounted within the interior of the stanchion tube 616. Further, a bypassflow channel around the piston is provided centrally through the pistonand other components, rather than through an annular passage. Thedampener 730 is illustrated in FIG. 17 with the slide tube 618 removed,but would be included to interact with the stanchion tube 616 the sameas in the embodiment of FIG. 13. Just as in the previously describeddampener 628, the dampener 730 includes a piston assembly 732 mounted ona piston shaft 734 that is secured to the slide tube (not shown). Thepiston assembly 732 is slidably received within a fluid chamber 736defined within the interior of the lower end of the stanchion tube 616.An annular bearing and seal head assembly 738 and snap retaining ring isreceived within the lowermost end of the stanchion tube 616 and forms aslidable seal with the piston shaft 734 below the piston assembly 732.The fluid chamber 736 may contain either a compressible orincompressible fluid, and in a preferred embodiment illustrated containsa compressible gas such as air or nitrogen. For use with a gas, as ispreferred, the piston preferably includes only rebound passages andrebound shim washers, with all compression stroke gas flow occurringthrough the bypass channel, to be described. Alternately, compressionpassages and shims may also be included, particularly if a hydraulic oilis utilized instead of gas.

The upper end of the piston shaft 734 includes a central bore 740 (FIGS.17 and 19) that slidably receives the lowermost end of an extension tube742. The uppermost end of the extension tube 742 is fixably secured to avalve platform 744, as shall be described subsequently. The extensiontube 742 is aligned on the longitudinal axis of the stanchion tube 616and the piston shaft 734. As the piston shaft 734 and piston assembly732 carried thereon move upwardly and downwardly during compression andrebound, the extension tube 742 slides through the piston assembly 732and into the lowermost portion of the central bore 740.

Referring to FIGS. 17 and 18, the cylindrical valve platform 744 issecured within and sealed to the interior surface of the stanchion tube616, above the fluid chamber 736. The valve platform 744 again includesa recessed side 746. An outlet passage 748 is formed centrally into thelowermost side of the valve platform 744, extending upwardly and partway along the recessed side 746. The upper end of the extension tube 742is press fit or otherwise secured to and sealed within this firstpassage 748. A fluid flow path is thus formed into the extension tube742 from the recessed side 746 of the valve platform 744.

A second longitudinal inlet passage 750 is defined longitudinally intothe bottom side of the valve platform 744, offset radially from theoutlet passage 748 on the side opposite of the recessed side 746. Thesecond passage 750 terminates in a radial bypass reservoir bore 752,placing the inlet passage 750 in fluid flow communication with a chamber745 defined by the recessed side 746. A fluid flow path is thus formedfrom the fluid chamber 736 through the valve platform 744 to the bypassreservoir chamber 745. Control of fluid flow through the inlet passage750 and radial bore 752 is controlled by a bender 754. The bender 754has an upper end mounted by a clamp 756 to the upper end of the valveplatform 744. The bender 754 then extends downwardly through a passage758 defined in the upper end of the valve platform 744, and extends intoa secondary chamber 760 defined within the bypass reservoir chamber 745.The secondary chamber 760 is longitudinally oriented and centrallyaligned with the outlet passage 748, and communicates at a lower endwith the bypass reservoir chamber 745. The radial bore 752 extends intothe secondary chamber 760 and is surrounded by a radially projecting,annular valve seat 762 defined by the valve platform 744.

The secondary chamber 760 is dimensioned such that fluid which flowsthrough the radial bore 752 can surround the bender 754 on all sides,and also freely communicate with the bypass reservoir chamber 745.Control of the flow of fluid, such as gas, through the inlet passage 750and radial bore 752 into the chambers 760 and 745 is controlled byautomatic adjustment of the biasing of the bender 754 respective to thevalve seat 762 and radial bore 752. When power is provided to the bender754 to flex it away from the valve seat 762, as shown in FIG. 18, fluidcan flow from the fluid chamber 736 through the inlet passage 750 andradial bore 752, into the secondary chamber 760 and the bypass reservoirchamber 745. Fluid is then free to flow down through the outlet passage748 and into the extension tube 742, as illustrated by the directionalflow arrows in FIG. 18. Referring to FIG. 19, fluid exits the extensiontube 742 into the central bore 740 of the piston shaft 734. From therethe fluid is free to continue through radial passages 764 defined in thewall of the piston shaft 734, into an annular chamber 766 surroundingthe piston shaft 734, and through outlets 788, back into the fluidchamber 736 below the piston assembly 732. Bypass flow to the back sideof the piston is selectively permitted depending on the operation of thebender 754. Operation of the bender 754 is controlled the same as in thepreviously described embodiment of FIG. 13 for variable dampening inresponse to piston travel and/or velocity. Thus, the dampener 730includes a circuit board 790 and battery 792 mounted on cross bracesinternally within the stanchion tube 616.

Again, modifications of the dampener of FIGS. 17-19 can be made withinthe scope of the present invention, as previously described with regardto the other embodiments.

While the preferred embodiments of the invention have been illustratedand described, it will be appreciated that various changes can be madetherein without departing from the spirit and scope of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A dampener for a shockabsorber including a stanchion tube, comprising:(a) a fluid chamberdefined at least partially within the stanchion tube and containingfluid; (b) a piston disposed within the fluid chamber for movementwithin the fluid chamber under the force of a shock acting on the shockabsorber, the piston having a first side and a second side; (c) a bypasschannel in fluid communication with the fluid chamber on the first sideof the piston and on the second side of the piston, the bypass channelpermitting fluid to operably bypass the piston while flowing from thefirst side of the piston to the second side of the piston; and (d) avalve disposed within the stanchion tube and operable to control theflow of the fluid through the bypass channel, wherein the valve includesa bender having a response material embedded within at least a portionthereof, the bender moving during displacement of the piston to controlthe flow of fluid through the bypass channel.
 2. The dampener of claim1, wherein the bender is operable to move in response to at least one ofthe extent of displacement of the piston and the velocity of pistondisplacement.
 3. The dampener of claim 2, wherein the response materialembedded within the bender comprises a piezoelectric material.
 4. Thedampener of claim 3, further comprising a sensor that detects a changein the compression of the shock absorber and a power supply electricallyconnected with the sensor and the piezoelectric material, to supplypower to bias the bender in response to the sensor for control of fluidflow through the bypass channel.
 5. The dampener of claim 4, wherein thebender, sensor and power supply are mounted within the stanchion tube.6. The dampener of claim 1, wherein the bender coacts with a valve seatdefined in the bypass channel.
 7. The dampener of claim 6, furthercomprising a valve body coupled to the bender, wherein movement of thebender moves the valve body relative to the valve seat to control theflow of fluid through the bypass channel.
 8. The dampener of claim 6,wherein at least a portion of the bypass channel and the valve seat aredefined by a valve platform mounted within the stanchion tube.
 9. Thedampener of claim 1, wherein the response material embedded within thebender comprises a piezoelectric material.
 10. The dampener of claim 1,further comprising a slide tube coaxially mounted with the stanchiontube for telescoping during compression and rebound of the shockabsorber.
 11. The dampener of claim 10, wherein the fluid chamber,piston, bypass channel and valve are all housed within the assembledstanchion tube and slide tube.
 12. The dampener of claim 1, wherein thefluid chamber, piston and valve are disposed along a common longitudinalaxis of the stanchion tube.
 13. A dampener for a shock absorberincluding a stanchion tube, comprising:(a) a fluid chamber defined atleast partially within the stanchion tube and containing fluid; (b) apiston disposed within the fluid chamber for movement within the fluidchamber under the force of a shock acting on the shock absorber, thepiston having a first side and a second side; (c) a bypass channel influid communication with the fluid chamber on the first side of thepiston and on the second side of the piston, the bypass channelpermitting fluid to operably bypass the piston while flowing from thefirst side of the piston to the second side of the piston; and (d) avalve disposed within the stanchion tube and operable to control theflow of the fluid through the bypass channel, further comprising a gaschamber defined at least partially within the stanchion tube andcontaining a compressible gas, wherein the gas chamber is separated fromthe fluid chamber by a floating chamber seal.
 14. The dampener of claim13, wherein at least a portion of the bypass channel passes through thechamber seal.
 15. The dampener of claim 14, wherein the portion of thebypass channel that passes through the chamber seal is defined within anextension tube having a first end perforating the chamber seal and asecond end extending through the gas chamber to a valve platform,thereby permitting fluid to flow from the fluid chamber to the valveplatform without fluid entering the gas chamber.
 16. The dampener ofclaim 1, wherein at least a portion of the bypass channel is definedwithin the stanchion tube and is disposed radially offset from thepiston.
 17. The dampener of claim 16, further comprising a hydraulicfluid sleeve received within the stanchion tube, the fluid chamber beingdefined by an interior of the sleeve, wherein the bypass channel isdefined at least partially between an exterior surface of the sleeve andthe stanchion tube.
 18. The dampener of claim 1, further comprising atube mounted within the fluid chamber and having a first end in fluidcommunication with the valve on the second side of the piston and asecond end that is slidably received through an aperture defined in thepiston, to permit the flow of fluid from the valve through the tube tothe first side of the piston.
 19. A dampener for a telescopingsuspension strut of a bicycle having a ground engaging wheel and aframe, comprising:(a) a stanchion tube having an end securable to one ofthe ground engaging wheel and the bicycle frame, and defining aninternal fluid chamber containing fluid; (b) a piston assembly includinga piston disposed within the fluid chamber and a shaft extendingtherefrom and securable to the other of the ground engaging wheel andthe bicycle frame, the piston having a first side and a second side andmoving within the fluid chamber under a force acting on the suspensionstrut; (c) a bypass channel in fluid communication with the fluidchamber on the first side of the piston and with the fluid chamber onthe second side of the piston, bypassing the piston therebetween; and(d) a valve disposed in fluid communication with the bypass channel toautomatically control the flow of the fluid through the bypass channelduring movement of the piston assembly relative to the stanchion tube,wherein the valve includes a bender having a response material embeddedwithin at least a portion thereof, the bender moving during displacementof the piston to control the flow of fluid through the bypass channel.20. The dampener of claim 19, wherein the piston assembly, bypasschannel and valve are all defined at least partially within thestanchion tube.
 21. The dampener of claim 19, further comprising a slidetube coaxially assembled with the stanchion tube for telescopiccompression, wherein the piston assembly, the bypass channel and thevalve are mounted internally within the stanchion tube and the slidetube.
 22. A dampener for a shock absorber, comprising:(a) a housingdefining an interior surface; (b) a sleeve received within the interiorsurface of the housing, and at least partially defining a fluid chambercontaining fluid; (c) a piston disposed within the fluid chamber formovement within the fluid chamber under the force of a shock acting onthe shock absorber, the piston having a first side and a second side;(d) a bypass channel defined at least partially between the sleeve andthe housing, and in fluid communication with the first side of thepiston and the second side of the piston, and bypassing the pistontherebetween; and (e) a valve operable to control the flow of the fluidthrough the by pass channel, wherein the valve includes a bender havinga response material embedded within at least a portion thereof, thebender moving during displacement of the piston to control the flow offluid through the bypass channel.
 23. The dampener of claim 22, whereinthe fluid chamber defines first and second ports disposed on first andsecond sides of the piston, wherein the bypass channel places the firstport in communication with the second port, passing between the sleeveand the housing therebetween.
 24. The dampener of claim 23, wherein thebypass channel is defined by an annular space formed between the sleeveand the interior surface of the housing.
 25. A dampener for a shockabsorber, comprising:(a) a housing defining a fluid chamber having firstand second ends and containing fluid; (b) a piston disposed within thefluid chamber and movable between the first and second ends of the fluidchamber in response to shock acting on the shock absorber; (c) a tubemounted within the housing and having a first end secured to the housingand a second end slidably received within a passage defined through thepiston, the piston sliding on the tube during movement within thechamber, the tube defining a bypass channel in fluid communication at afirst end of the bypass channel with the first end of the fluid chamberand at a second end of the bypass channel with the second end of thechamber; and (d) a valve disposed at least partially within the housingand in fluid communication with the bypass channel to control the flowof fluid therethrough, wherein the valve includes a bender having aresponse material embedded within at least a portion thereof, the bendermoving during displacement of the piston to control the flow of fluidthrough the bypass channel.
 26. The dampener of claim 25, wherein thepiston is carried on a piston shaft, the piston shaft and the tube beingaligned along a common longitudinal axis, the piston shaft defining anaxial passage into which the tube is slidably received, furthercomprising at least one port defined in the piston from the axialpassage to the fluid chamber to permit fluid flow from the first end ofthe fluid chamber, through the tube through the axial passage and portinto the second end of the fluid chamber.
 27. The dampener of claim 26,wherein the fluid comprises a compressible gas.